1. Field
Aspects of embodiments of the present invention relate to a battery module.
2. Description of the Related Art
As industries of electronics, communications and the like are rapidly developed, the spread of portable electronic devices such as a camcorder, a cellular phone and a notebook PC has recently been increased. Accordingly, the use of secondary batteries has also been increased. The secondary batteries can be used for not only portable electronic devices but also medium-and large-sized apparatuses, such as an electric tool, an automobile, a space transportation means, a motorbike, a motor scooter and an aerial transportation means, which require high output and high power. The secondary batteries used for the medium-and large-sized apparatuses constitute a large-capacity battery module or battery pack by connecting a plurality of battery cells in series or parallel.
A bus bar may be used to connect battery cells in series or parallel as described above. In this case, when the bus bar is welded or fastened to a terminal portion of the battery cell, a difference in height between adjacent battery cells may occur, and, therefore, welding may not be uniformly performed on the terminal portion of the battery cell. Accordingly, various studies on a method for overcoming a step difference between battery cells have been conducted.